AIR PUMP HTR, what is it?

Ok, I have a 2012 DC LB 4X4 SR5, no seat heater. I looked under the little aux relay box, next to the main fuse/relay panel under the hood; there is only 1 relay... for the fog lights, but there is an empty relay socket wired, and the little lid says AIR PUMP HTR, anyone know what this is? My truck did not have a relay for this slot.
The red/black wire (lower right in first pic) for the fog relay has 12v power only when the lights are on, the blue wire with white tracer (above the green wires in first pic) has 12v power when the the key is set to ON and also when the engine is running, regardless of headlights off/low/high.... which is how I'd like to do my "anytime fog lights mod", I would swap these two wires. I just dont know what this empty spot is, which is labled AIR PUMP HTR; Will this always have power when the truck is ON? Is this a good 12v power lead to do my mod?

Any help here is greatly appreciated.

Jesse

 

If you do a little www.google.com, you might find the answers -
Did a quick search....

Here's a PDF of a corolla fuse box.
http://www.toyota.com/t3Portal/document/om/OM12A23U/pdf/8.pdf

Scroll down...

40. AIR PUMP 50 A (1.8 L 4−cylinder
[2ZZ−GE] engine): Emission control
system
41. HTR 40 A: Air conditioning system

And from tacoma manuals ANd don't forget....this fuse box could be the same fuse box/lid used for a variety of different Toyota vehicles. If you are still confused - go to your dealer and ask them.

 

Thanks, but that relay spot was empty, so it cant be A/C.
There are wires under that spot (right above the blue fog light relay), just no relay...... what is that for?

Jesse

 

Does swapping the 2 wires work?

 

Yes, but remember to turn the fogs off when you park........

Jesse

 

Janster no need to be so rude about it, not everyone has the apparent time as you do to spend searching the black wholes of the internet. And your second ncttora link has diddley squat to do with that relay. He asked what it is, and if he could use it as a power source. Simply question/simple answer.

Now to answer his question, it is a emission control device for the 2.7l that is not equipped on your truck, therefore yes you can use this as a power source for mods.

 

Hey noob here yes, noob in general not. The comment is plainly put, when you see guys like the OP and myself it should be understood that we maybe have lives going on and dont have the hours to put in front of a computer to generate 10k and 30k plus posts.

However it is noted, and I will structure my comments in the future as to not be considered offensive. But as you told me to calm down, take a second to think maybe my comment was meant just the same as yours to me.

Food for thought.

 

Please re read what I said sir.. I will restructure as not to offend yourself or other, now I think OP's thread has been jacked enough, end of conversation.

 

Reviving this thread as I just noticed I am missing this AIR PUMP HTR relay as well. I found out when trying to do the anytime fog mod. Everything works fine but I am curious as to why I don’t have this relay and noticed pretty much everybody else in that thread (ND4 anytime fog) has this relay. What potential functionality have I been missing out on, do I continue to leave it missing or try to source a relay and shove it in. I bought this car used March of 2021 and it’s a my 2012 trd off-road 4x4 4.0L sbdc

 

do you have an air injection pump on your truck? I believe Toyota started putting them in 2012-2013 timeframe. If you have no air pump then there's no need for the air pump heater or associated relay.

 

the secondary air pump? the one people do the UNI air filter mod for? If so, then yes I have that, and actually just did the UNI mod. Does this mean my secondary air pump hasn't been running?

 

Additionally, can anybody pull their AIR PUMP HTR relay and tell me what the part number is? visually it looks like the Fog relay from below fits it but I just want to make sure its the same one before I try out the Fog relay. Also, can anybody tell me how to check if the air pump is working; i.e. if I take the cover off the secondary air pump, will I be able to visually inspect the fan blade spinning, if so, is it always spinning when the motor is on, or when should I expect to see it spinning to see if its working.

 

I believe it only comes on during cold start and maybe when you turn the engine off? I don't know because mine is a 2010 so I don't have that junk in the engine bay. If it's only the heater, i believe during a cold temp start the ECM heats up the air it is injecting into the exhaust, so without that relay you may be losing some efficiency. This is schematic from a tundra I couldn't find my 2012 taco schematics but it should be very similar. You should be able to hear the pump "whoosh" when you turn off the truck, the heater being out of service should not have any affect on the pump itself not working.

 

The documents I've been reading say the heater is only applicable to automatic trans taco as well, so maybe that's why some don't have this installed. Do you have the 6 speed or automatic?

 

I have the automatic transmission. I’m still scratching my head as to why it’s missing. Maybe the previous owner blew his fog relay and found it convenient to just take the one next to it? :shrug: If it is just the heating element, then I wouldn’t even know how to test it.

 

I'm thinking you would expect a MIL if you had that relay missing, something like a P144C or P144D? It could be the PO "borrowed" that relay and never put it back. Have you checked to see if you have any pending MILs?

 

Looking at diagrams for 2012 and 13 it only shows up on the 13 and up diagrams so my guess is you have a late build 12 model and they changed the fuse box/wiring harness but didn't yet add the relay or heater.

 

That makes sense, and the PCM probably is not looking for that MIL. Easy way to check could be to look at the air pump connector, if it has 4 wires it has a heater and if it only has 2 wires it came without the heater.

 

I can't find any reference to the purpose of the heater anywhere, it can't be much of a heater being only a 10A fuse feeding both it and the switching valve, I guess someone will have to autopsy a dead pump and see what it is actually doing

 

yep I can’t imagine it doing a whole lot either. Given the previous reliability and issues with the pumps it won’t be long before one fails LOL